1. Field of the Invention
The present invention generally relates to a display technology of a mobile terminal in a mobile broadcast system. More particularly, the present invention relates to a method, apparatus and system for controlling a scene structure of a mobile terminal for receiving and displaying data streams in a mobile broadcast system.
2. Description of the Related Art
Lightweight Application Scene Representation (LASeR) is the format of multimedia content for a simple multimedia service in terminals such as mobile phones which may suffer from communication resource shortages. The LASeR is analogous to the technology of the Moving Picture Experts Group-4 Binary Format for Scene (MPEG-4 BIFS). The BIFS is the scene description standard for all multimedia contents and the LASeR is the scene description standard for multimedia terminals such as mobile phones small display sizes and a reduced network bandwidth.
The BIFS is used for an object-based system. In the object-based system, multimedia is a set of objects. Temporal and spatial information of each of the media must be indicated. For example, when the weather forecast is broadcast, four objects such as a weather caster, a weather chart displayed behind the weather caster, speech of the weather caster, and background music can be considered. When the multiple objects are present independently, an appearing time, disappearing time and position of each object should be defined to describe one scene. This definition is the BIFS. Because related information is stored in a binary file according to the BIFS, the storage capacity is reduced.
However, the BIFS has a large amount of data of about 200 pages as described in the MPEG-4 system standard document (International Organization for Standardization/International Electro-technical Commission (ISO/IEC) 14496-1). It is difficult to use the BIFS in communication environments suffering from a shortage of available resources, such as in mobile terminals. An alternative plan is the LASeR. The LASeR is the technology developed for free representations of various multimedia and interactions with users in mobile terminals with limited memory and power by performing multiplexing and synchronization processes for different elementary streams (ESs) such as a scene description, video, audio, image, font, and metadata, and minimizing complexity. The ESs have the above-described generic meaning. The ESs are considered to be individual logical channels configuring multiple channels to be displayed.
The LASeR ES is constructed with an access unit (AU) including a command. The command is used to change the scene characteristic at a particular time. Simultaneous commands are grouped in one AU. The AU may be one scene image, short sound, one graphic image, or short animation. A LASeR browser displays ESs in a designated order. The hierarchy is present between the ESs. The LASeR browser displays scenes in order of: (1) packet reception, (2) packet decoding (AU-by-AU recovery of one image and one video clip, among others), (3) command execution, (4) audio/video object rendering, (5) user interaction (selection and dragging, among others), and (6) local connection or connection with an external information source.
Alternatively, the standardization for the convergence of the LASeR and World Wide Web Consortium (W3C) is ongoing. Specifically, the 3rd Generation Partnership Project (3GPP) employs a scalable vector graphics (SVG) standard of the W3C for graphic or animation representation. When the SVG standard is employed, audio, video, characters, images and polyhedrons may be represented. In relation to the SVG, the conventional LASeR technology has been proposed only to compose a movie tile using a clip path of SVG 1.1 such that a channel mosaic service for multiple channels is provided. Using the LASeR technology in a mobile terminal creates a problem in identifying channel stream content in service when a screen image of the mobile terminal is tiled. Using the LASeR technology in a mobile terminal facilitates the display of channels because a screen size of the mobile terminal is smaller than those of terminal and personal computer (PC) systems for receiving existing broadcast services.
For example, the currently proposed stream source technology for composing a multi-channel image displays multiple broadcast service channels on one image by multiplexing multiple images into one channel for the channel mosaic service and allocating an additional encoded mosaic service channel. When the channel mosaic service is applied to mobile broadcasting, significant costs are required for the network infrastructure construction. When limited channel resources are considered, it is difficult to actually implement one video channel dedicated for the mosaic service. When multiple images are to be processed in a stream source scheme and are multiplexed and encoded into one channel, the image quality may be degraded.
Accordingly, there is a need for an improved system and method for accurately implementing one video channel dedicated for a mosaic service when limited channel resources are considered and to reduce the degradation of image quality.